The scientists found out what happens during hypoxia when levels of the hormone serotonin are disturbed in pacemaker cells, which resets the normal breathing pattern for babies. Normal serotonin levels are needed in these respiratory pacemakers to induce gasping and ignite auto-resuscitation.

Scientists knew that SIDS victims had disturbed levels of serotonin in areas critical for respiration. Since serotonin regulates the sodium channels in pacemaker cells, the research team examined more closely serotonin levels in sodium-driven pacemaker neurons in the breathing centre.

When they removed serotonin from these pacemaker cells, the gasping drastically decreased, from typically about 20 gasps to just two or three gasps. "It indicates that if there's a problem with serotonin, the gasping is gone," said Jan-Marino Ramirez, a professor of organismal biology and anatomy. "And when these children don't gasp, they don't wake up."

According to the researcher, when the body senses a lack of oxygen, it shuts down most of the cellular respiratory network and focuses its energy on gasping, which is modulated solely by sodium-driven pacemaker neurons. If that specific neuron is blocked, for whatever reason, the body cannot gasp.

"Gasping is an important arousal or auto-resuscitation mechanism," Ramirez said. It resets a baby's normal breathing rhythm and also alerts the baby as well as the mother that something is wrong.

Disturbed serotonin levels are also implicated in many psychiatric conditions, such as depression, bipolar disorder and attention deficit disorder. According to Ramirez, adults suffering with these types of conditions may be survivors of SIDS.